Magnetic bearings are bearings that use electromagnetic forces to support a load. Magnetic bearings may support moving machinery without physical contact. For example, they can levitate a rotating shaft, providing for rotation with very low friction and no mechanical wear. Active magnetic bearings use electromagnetic suspension, and may include an electromagnet assembly, power amplifiers configured to drive the electromagnets, a controller, and sensors (e.g., gap sensors) with associated electronics. The power amplifiers drive electromagnets on opposing sides of the shaft. The sensors provide feedback to control the position of the rotor within the gap. The controller offsets the current to drive the electromagnets as the rotor deviates from its desired position.
U.S. Pat. No. 5,578,880 issued to Lyons et al. on Nov. 26, 1996 discloses a fault tolerant active magnetic bearing system that comprises a magnetic bearing having a rotor mounted for rotation within a stator and for coupling to a shaft. An electric power distribution system is energized from a multi-phase switched reluctance machine supplying three independent DC power buses. Each of the power buses is coupled for supplying power to a respective pair of diametrically opposite electromagnets of the magnetic bearing so as to establish multiple magnetic control axes. Multiple power controllers are each operatively connected in circuit with a separate respective power bus. The power controllers include independent power control systems each coupled to a respective pair of diametrically opposite electromagnets for independently controlling energization of each one of the pair of diametrically opposite electromagnets.
The present disclosure is directed toward overcoming one or more problems discovered by the inventors or that is known in the art.